The composite design pattern is a structural pattern that allows building complex structures out of simple components. It’s a way to treat individual objects and compositions of objects in the same way. In Swift, you can implement this pattern by using classes and protocols.
The composite design pattern should be used when you need to treat individual objects and compositions of objects in the same way. For example, when you have a tree-like structure, where you have a parent object that contains children objects, and those children can be either a single object or a composition of objects.
The composite design pattern is built around two main components: the component and the composite. The component is an abstract class or protocol that defines the basic behavior of an object. The composite is a concrete class that implements the component and contains children objects.
Let's consider an example of a file system, where we have files and folders. Folders can contain other files and folders, and we want to be able to treat them in the same way, for example, to display the size of a file or folder.
Let's start by defining the `FileSystem` protocol:
Let's start by defining the `FileSystem` protocol:
Next, we create the `File` class that conforms to the protocol:
Similarly, let's create the `Folder` class that also conforms to the `FileSystem` protocol:
With these classes in place, we can now create a tree structure using the File and Folder classes. For example:
The composite design pattern is a useful tool when dealing with complex structures composed of simple components. By treating individual objects and compositions of objects in the same way, it becomes easier to build and maintain a tree-like structure. In Swift, you can implement this pattern using classes and protocols.
